1 . Field of the Invention
The present invention relates to torque screwdrivers. More particularly, the present invention is related to a torque screwdriver, including means to selectively advance the calibrated torque screwdriver in various measurement units. It will precisely position and coordinate indexing numerals on an adjustment cap with other indexing numerals included on the shaft, allowing the operator the ability to select a preset torque value.
2. Background Art
In the past, manufacturers of torque screwdrivers have only had means to advance settings up or down by bringing an indicator mark even with lines on a scale. Such a method is highly disadvantageous in that the scales are divided into lines every 5, 10 or 20 unit increments, or some similar unit increment arrangement. These exact unit increments cause the operator to select only such exact unit increments as shown on the shaft, or guess what the value settings might be between the included incremental lines. This drastically decreases the accuracy of the operator's torque value setting choices.
A search of the background art directed to the subject matter of the present invention conducted in the U.S. Patent and Trademark Office disclosed the following U.S. Pat. Nos.:
______________________________________ 2,440,683 Hattan 3,896,540 Ellis 2,491,325 Mcvey 4,063,474 Klopping 2,729,134 Stanton 4,901,610 Larson 2,933,959 McMahon 5,501,124 Ashby 3,001,430 Cranford 5,662,012 Grabovac ______________________________________
A thorough review of the above-identified patents has concluded that none are believed to claim teach or disclose the particular novel combination of elements and functions set forth in the present invention. While U.S. Pat. Nos. 2,933,959, 3001,430, 4,063,474, and 4,901,610 all include index markings on the shaft, it will be seen that these are the type referred to above where any choice of torque pressure other than indicated by the indexing lines, is merely a matter of guesswork.
Accordingly, it is the object of the present invention to further divide each division into positive incremental and indexable values, making possible increased operator selection for a greater value of torque value settings than has been available in the prior art.
Another object of the present invention is to be sure that each one of the torque value settings is an accurate torque value, eliminating the need for guesswork.